Urban heat islands – ‘the biggest threat to African cities’

Published on: 23 Feb 2016

Escalating temperatures in the world’s major urban capitals requires new thinking from the design community

The remnants of modernist planning to get as many cars and people into as small a space as possible, has created urban areas that are hotter than their surrounding rural areas, creating an effect identified as ‘urban heat islands’. New research currently underway in China and India indicates that this urban heat island effect is contributing to climate warming by almost 30%. If future generations are to live in cities, the World Health Organisation (WHO) says, the urban heat islands, which both raise temperatures and trap pollutants, have to be reduced this century.

During the summer of 2015-2016 new record midday temperatures were recorded in South Africa’s six big cities, with the thermometer going into the high 30s and low 40s. In South Africa, where the United Nations estimates that 71.3% of the population will live in urban areas by 2030 (nearly 80% by 2050), the issue of urban heat could be catastrophic. The WHO estimates that air pollution and heat stress kill about four million people a year, as the combination of hot days and nights weakens the body to a level where it cannot recover.

Research by the City of Johannesburg for its 2040 strategy shows that, if not tackled, climate change will pile pressure on top of the existing urban heat island and see temperatures in summer push closer towards 50°C, rather than the high 30s that are now common. But, in line with other major metropoles around the world, plans are being imagined across various sectors to tackle what can still be changed. In Johannesburg the “corridors of freedom” initiative, a series of well-planned transport arteries, will also try to use the shift in transport to change the spatial dynamic of the city, mixing low-cost and high-cost housing projects with business districts so people do not have to travel as much. “Apartheid social planning has left the city with sprawling low-density areas without viable transport systems. The majority of working class and poor citizens are still living on the fringes of the CBD and have to commute distances to get to work.” The city says of the projects which they intend to complete the first phase of by this year.

With the world already, on average, nearly 1°C hotter than it was before the industrial revolution kicked off, and Southern Africa experiencing a record-setting 2014 and 2015, the time to act unilaterally to reduce carbon emissions has never been more important.